In a conventional semiconductor device manufacturing process, fine circuit patterns have been formed by a photolithography technology using a photoresist. A side wall transfer (SWT) process or a double patterning (DP) process is under consideration as a way to further miniaturize circuit patterns.
The side wall transfer process using a photoresist as a core material requires a process of slimming only a photoresist pattern without damaging a bottom anti-reflection coating (BARC) film.
The slimming capability of the double patterning process, which utilizes a Litho-Litho-Etching (LLE) to control a line width of a resist pattern to fall within a range of 22 nm or less, may be limited by the resolution of an exposure apparatus. As such, the double patterning process requires an additional slimming process to slim down the line width of the resist pattern.
One example of such a slimming process modifies sidewalls of a resist pattern through the use of, e.g., liquid chemicals, thereby removing the sidewalls.
Patent Documents
In the slimming process of modifying the sidewalls of the resist pattern with the aforementioned liquid chemicals to remove the portions of the sidewalls, an amount to be slimmed depends on optical conditions and resist species, which makes it difficult to perform a high-precision control of the slimming process. In addition, such slimming process may result in a decrease in height of the resist.